Antibody isotype responses to egg antigens in human chronic Schistosomiasis mansoni before and after treatment

In the present communication we analyzed the levels of IgG1, IgG2, IgG3, IgG4 and IgE isotypes to soluble egg antigen of Schistosoma mansoni by ELISA in individuals from an endemic area for schistosomiasis in Northeast Brazil. The analysis was performed before and after treatment to evaluate the age-dependent pattern, and to identify differences in the reactivities to antigens. Our results suggest that schistosomiasis treatment would not interfere with this sort of immune response.

Antibody isotype responses in Balb/c mice immunized with the cytoplasmic repetitive antigen and flagellar repetitive antigen of Trypanosoma cruzi

In the present report we analyzed the levels of IgG1, IgG2a, IgG2b and IgG3 isotypes from Balb/c mice immunized with cytoplasmic repetitive antigen (CRA), and flagelar repetitive antigen (FRA) of Trypanosoma cruzi. The immunization was done by subcutaneous route three times (20 days apart) and the analysis was performed 14 days after each treatment. CRA-immunized mice produced high levels of all IgG isotypes, mainly IgG3 and IgG1. FRA-immunization elicited only high levels of IgG1.

Differential antibody isotype expression to the major Paracoccidioides brasiliensis antigen in juvenile and adult form paracoccidioidomycosis

We investigated the relationship between antibody response to the major Paracoccidioides brasiliensis antigen, a 43-kDa glycoprotein, and the two paracoccidioidomycosis (PCM) clinical presentations, the juvenile and the adult forms. Total immunoglobulin G (IgG), IgG isotypes, and IgA anti-gp43 antibodies were determined by enzyme-linked immunosorbent assay in patients' sera. Juvenile PCM patients had higher (P =.003) IgG anti-gp43 levels than adult form patients. IgG1 subclass levels, however, were comparable between the two clinical forms. Patients with the juvenile form had higher (P <.001) IgG4, but lower(P =.03) IgG2 levels than patients with the adult form. The IgG4 isotype, regulated by interleukin 4, was found in all juvenile form patients but in only 12% of the adult form patients. In contrast, high levels of the IgG2 isotype, regulated by interferon-gamma, were found in 41% of the adult PCM patients, mainly those with a more benign disease, but in only 12% of the juvenile patients. IgG3 was either absent or detected at low levels. These results demonstrate, for the first time, specific IgG4 antibodies in the humoral immune response of patients with an endemic deep mycosis and suggest that the switch to the IgG subclasses in PCM is regulated by the patients' T-helper subset (Th-l or Th-2) dominant cytokine profile. A possible role for IgG4 in the immunopathogenesis of the juvenile, more severe form of the disease is discussed. Finally, IgA was found mainly in adult form patients, probably as a result of the chronic mucosal antigenic stimulation characteristic of this form. (C) Elsevier, Paris.

Schistosomiasis in the People's Republic of China: Prospects and challenges for the 21st century

Schistosomiasis japonica is a serious communicable disease and a major disease risk for more than 30 million people living in the tropical and subtropical zones of China. Infection remains a major public health concern despite 45 years of intensive control efforts. It is estimated that 865, 000 people and 100,250 bovines are today infected in the provinces where the disease is endemic, and its transmission continues. Unlike tire other schistosome species known to infect humans, the oriental schistosome, Schistosoma japonicum, is a true zoonotic organism, with a range of mammalian reservoirs, making control efforts extremely difficult. Clinical features of schistosomiasis range from fever; headache, and lethargy to severe fibro-obstructive pathology leading to portal hypertension, ascites, and hepatosplenomegaly, which can cause premature death. Infected children ale stunted and have cognitive defects impairing memory and learning ability. Current control programs are heavily based on community chemotherapy with a single dose of the drug praziquantel, but vaccines (for use in bovines and humans) in combination with other control strategies ale needed to make elimination of the disease possible. In this article, we provide an overview of the biology, epidemiology clinical features, and prospects for cona ol of oriental schistosomiasis in the People's Republic of China.

Human susceptibility to Schistosoma japonicum in China correlates with antibody isotypes to native antigens

Antibody isotypic responses (IgE, IgA, IgG1, IgG2, IgG3 and IgG4) to Schistosoma japonicum antigens-adult worm (AWA), soluble egg (SEA) and the recombinant proteins TEG (22.6-kDa tegumental antigen, Sj22) and PMY (paramyosin, Sj97)-were measured (in 1998) in a cohort of 179 Chinese subjects 2 years post-treatment. Subjects in the highest intensity re-infection group (> 100 eggs per gram faeces) had significantly higher levels of IgG1 and IgG4 against AWA. Analysis of IgG4/IgE ratios for AWA and SEA linked IgG4 excess to re-infection and IgE excess to non-re-infection. Two years after chemotherapeutic cure, 29 subjects, who were re-infected or never infected but highly water-exposed, were classified as epidemiologically susceptible (n = 15) or epidemiologically insusceptible to infection (n = 14). IgG4 levels against native antigens (AWA and SEA) were higher in susceptibles and IgE levels were higher in insusceptibles but antibody responses to the recombinant proteins (PMY and TEG) showed no clear pattern or difference between susceptibility groups. These and earlier findings provide evidence that immunity develops against schistosomiasis japonica in China and that susceptibility/resistance correlates with antibody isotypes against native schistosome antigens.

Virus-like particles induce robust human T-helper cell responses.

Among synthetic vaccines, virus-like particles (VLPs) are used for their ability to induce strong humoral responses. Very little is reported on VLP-based-vaccine-induced CD4(+) T-cell responses, despite the requirement of helper T cells for antibody isotype switching. Further knowledge on helper T cells is also needed for optimization of CD8(+) T-cell vaccination. Here, we analysed human CD4(+) T-cell responses to vaccination with MelQbG10, which is a Qβ-VLP covalently linked to a long peptide derived from the melanoma self-antigen Melan-A. In all analysed patients, we found strong antibody responses of mainly IgG1 and IgG3 isotypes, and concomitant Th1-biased CD4(+) T-cell responses specific for Qβ. Although less strong, comparable B- and CD4(+) T-cell responses were also found specific for the Melan-A cargo peptide. Further optimization is required to shift the response more towards the cargo peptide. Nevertheless, the data demonstrate the high potential of VLPs for inducing humoral and cellular immune responses by mounting powerful CD4(+) T-cell help.

Virus-like particles induce robust human T-helper cell responses

Among synthetic vaccines, virus-like particles (VLPs) are used for their ability to induce strong humoral responses. Very little is reported on VLP-based-vaccine-induced CD4(+) T-cell responses, despite the requirement of helper T cells for antibody isotype switching. Further knowledge on helper T cells is also needed for optimization of CD8(+) T-cell vaccination. Here, we analysed human CD4(+) T-cell responses to vaccination with MelQbG10, which is a Qβ-VLP covalently linked to a long peptide derived from the melanoma self-antigen Melan-A. In all analysed patients, we found strong antibody responses of mainly IgG1 and IgG3 isotypes, and concomitant Th1-biased CD4(+) T-cell responses specific for Qβ. Although less strong, comparable B- and CD4(+) T-cell responses were also found specific for the Melan-A cargo peptide. Further optimization is required to shift the response more towards the cargo peptide. Nevertheless, the data demonstrate the high potential of VLPs for inducing humoral and cellular immune responses by mounting powerful CD4(+) T-cell help.

The role of APRIL and BAFF in lymphocyte activation.

The TNF family ligands BAFF (also called BLyS) and APRIL regulate lymphocyte survival and activation. BAFF binds to three receptors, BAFF-R, TACI and BCMA, whereas APRIL interacts with TACI, BCMA and proteoglycans. The contribution of BAFF and APRIL to B-cell and plasma-cell survival, CD154 (CD40L)-independent antibody isotype switching, germinal center maintenance, T-dependent and T-independent antibody responses, and T cell co-stimulation are relatively well understood. Constitutive BAFF produced by stromal cells determines the size of the peripheral B cell pool, whereas inducible BAFF produced by myeloid and other cells supports local survival of B lymphocytes and can be associated with development of autoimmunity when deregulated.

Isotype distribution of anticardiolipin antibodies in systemic lupus erythematosus prospective analysis of a series of 100 patients

A prospective study of IgG and IgM isotypes of anticardiolipin antibodies (aCL) in a series of 100 patients with systemic lupus erythematosus was carried out. To determine the normal range of both isotype titres a group of 100 normal control serum samples was studied and a log-normal distribution of IgG and IgM isotypes was found. The IgG anticardiolipin antibody serum was regarded as positive if a binding index greater than 2.85 (SD 3.77) was detected and a binding index greater than 4.07 (3.90) was defined as positive for IgM anticardiolipin antibody. Twenty four patients were positive for IgG aCL, 20 for IgM aCL, and 36 for IgG or IgM aCL, or both. IgG aCL were found to have a significant association with thrombosis and thrombocytopenia, and IgM aCL with haemolytic anaemia and neutropenia. Specificity and predictive value for these clinical manifestations increased at moderate and high anticardiolipin antibody titres. In addition, a significant association was found between aCL and the presence of lupus anticoagulant. Identification of these differences in the anticardiolipin antibody isotype associations may improve the clinical usefulness of these tests, and this study confirms the good specificity and predictive value of the anticardiolipin antibody titre for these clinical manifestations.

Cellular and humoral immune responses against the Plasmodium vivax MSP-119 malaria vaccine candidate in individuals living in an endemic area in north-eastern Amazon region of Brazil

Abstract Background Plasmodium vivax merozoite surface protein-1 (MSP-1) is an antigen considered to be one of the leading malaria vaccine candidates. PvMSP-1 is highly immunogenic and evidences suggest that it is target for protective immunity against asexual blood stages of malaria parasites. Thus, this study aims to evaluate the acquired cellular and antibody immune responses against PvMSP-1 in individuals naturally exposed to malaria infections in a malaria-endemic area in the north-eastern Amazon region of Brazil. Methods The study was carried out in Paragominas, Pará State, in the Brazilian Amazon. Blood samples were collected from 35 individuals with uncomplicated malaria. Peripheral blood mononuclear cells were isolated and the cellular proliferation and activation was analysed in presence of 19 kDa fragment of MSP-1 (PvMSP-119) and Plasmodium falciparum PSS1 crude antigen. Antibodies IgE, IgM, IgG and IgG subclass and the levels of TNF, IFN-γ and IL-10 were measured by enzyme-linked immunosorbent assay. Results The prevalence of activated CD4+ was greater than CD8+ T cells, in both ex-vivo and in 96 h culture in presence of PvMSP-119 and PSS1 antigen. A low proliferative response against PvMSP-119 and PSS1 crude antigen after 96 h culture was observed. High plasmatic levels of IFN-γ and IL-10 as well as lower TNF levels were also detected in malaria patients. However, in the 96 h supernatant culture, the dynamics of cytokine responses differed from those depicted on plasma assays; in presence of PvMSP-119 stimulus, higher levels of TNF were noted in supernatant 96 h culture of malaria patient’s cells while low levels of IFN-γ and IL-10 were verified. High frequency of malaria patients presenting antibodies against PvMSP-119 was evidenced, regardless class or IgG subclass.PvMSP-119-induced antibodies were predominantly on non-cytophilic subclasses. Conclusions The results presented here shows that PvMSP-119 was able to induce a high cellular activation, leading to production of TNF and emphasizes the high immunogenicity of PvMSP-119 in naturally exposed individuals and, therefore, its potential as a malaria vaccine candidate.

DNA vaccination against the novel tumor antigen, MUC18, for the therapy of metastatic melanoma

Melanoma patients with metastases have a very low survival rate and limited treatment options. Therefore, the targeting of melanoma cells when they begin to invade and metastasize would be beneficial. A specific adhesion molecule that is upregulated at the vertical growth phase is the melanoma cell adhesion molecule (MCAM/MUC18). MUC18 is expressed in late primary and metastatic melanoma with little or no expression on normal melanocytes. MUC18 has been demonstrated to have a role in the progression and metastasis of human melanoma. We utilized the alphavirus-based DNA plasmid, SINCp, encoding full length human MUC18 for vaccination against B16F10 murine melanoma cells expressing human MUC18. The alphavirus-based DNA plasmid leads to the expression of large quantities of heterologous protein as well as danger signals due to dsRNA intermediates produced during viral replication. In a preventative primary tumor model and an experimental tumor model, mice vaccinated against human MUC18 had decreased tumor incidence and reduced lung metastases when challenged with B16F10 murine melanoma cells expressing human MUC18. In a therapeutic tumor model, vaccination against human MUC18 reduced the tumor burden in mice with pre-existing lung metastases but did not have a significant effect on therapeutic vaccination in a primary tumor model. We next cloned murine MUC18 into SINCp for use in determining the efficacy of vaccination against murine MUC18 in a syngeneic animal model. Mice were vaccinated and challenged in a primary tumor and experimental metastasis model. In both models, vaccination significantly reduced tumor incidence and lung metastases. Humoral and cell-mediated responses were then determined. Flow cytometry and immunohistochemistry showed that specific antibodies were developed from vaccination against both human and murine MUC18. IgG2a antibody isotype was also developed indicating a Th1 type response. ELISPOT results showed that mice vaccinated against human MUC18 created a specific T cell response to targets expressing human MUC18. Mice vaccinated against murine MUC18 raised specific effector cells against target cells expressing murine MUC18 in a cell killing assay. These results indicate that vaccination against MUC18 developed specific immune responses against MUC18 and were effective in controlling tumor growth in melanoma expressing MUC18. ^

Th1 immune responses can be modulated by varying dimethyldioctadecylammonium and distearoyl-sn-glycero-3-phosphocholine content in liposomal adjuvants

Objectives - Cationic liposomes of dimethyldioctadecylammonium bromide (DDA) combined with trehalose 6,6'-dibehenate (TDB) elicit strong cell-mediated and antibody immune responses; DDA facilitates antigen adsorption and presentation while TDB potentiates the immune response. To further investigate the role of DDA, DDA was replaced with the neutral lipid of distearoyl-sn-glycero-3-phosphocholine (DSPC) over a series of concentrations and these systems investigated as adjuvants for the delivery of Ag85B–ESAT-6-Rv2660c, a multistage tuberculosis vaccine. Methods - Liposomal were prepared at a 5?:?1 DDA–TDB weight ratio and DDA content incrementally replaced with DSPC. The physicochemical characteristics were assessed (vesicle size, zeta potential and antigen loading), and the ability of these systems to act as adjuvants was considered. Key findings - As DDA was replaced with DSPC within the liposomal formulation, the cationic nature of the vesicles decreases as does electrostatically binding of the anionic H56 antigen (Hybrid56; Ag85B-ESAT6-Rv2660c); however, only when DDA was completed replaced with DSPC did vesicle size increase significantly. T-helper 1 (Th1)-type cell-mediated immune responses reduced. This reduction in responses was attributed to the replacement of DDA with DSPC rather than the reduction in DDA dose concentration within the formulation. Conclusion - These results suggest Th1 responses can be controlled by tailoring the DDA/DSPC ratio within the liposomal adjuvant system.

Th1 immune responses can be modulated by varying dimethyldioctadecylammonium and distearoyl-sn-glycero-3-phosphocholine content in liposomal adjuvants

Objectives Cationic liposomes of dimethyldioctadecylammonium bromide (DDA) combined with trehalose 6,6′-dibehenate (TDB) elicit strong cell-mediated and antibody immune responses; DDA facilitates antigen adsorption and presentation while TDB potentiates the immune response. To further investigate the role of DDA, DDA was replaced with the neutral lipid of distearoyl-sn- glycero-3-phosphocholine (DSPC) over a series of concentrations and these systems investigated as adjuvants for the delivery of Ag85B-ESAT-6-Rv2660c, a multistage tuberculosis vaccine. Methods Liposomal were prepared at a 5: 1 DDA-TDB weight ratio and DDA content incrementally replaced with DSPC. The physicochemical characteristics were assessed (vesicle size, zeta potential and antigen loading), and the ability of these systems to act as adjuvants was considered. Key findings As DDA was replaced with DSPC within the liposomal formulation, the cationic nature of the vesicles decreases as does electrostatically binding of the anionic H56 antigen (Hybrid56; Ag85B-ESAT6-Rv2660c); however, only when DDA was completed replaced with DSPC did vesicle size increase significantly. T-helper 1 (Th1)-type cell-mediated immune responses reduced. This reduction in responses was attributed to the replacement of DDA with DSPC rather than the reduction in DDA dose concentration within the formulation. Conclusion These results suggest Th1 responses can be controlled by tailoring the DDA/DSPC ratio within the liposomal adjuvant system. © 2013 Royal Pharmaceutical Society.

Intestinal bacteria condition dendritic cells to promote IgA production.

Immunoglobulin (Ig) A represents the predominant antibody isotype produced at the intestinal mucosa, where it plays an important role in limiting the penetration of commensal intestinal bacteria and opportunistic pathogens. We show in mice that Peyer's Patch-derived dendritic cells (PP-DC) exhibit a specialized phenotype allowing the promotion of IgA production by B2 cells. This phenotype included increased expression of the retinaldehyde dehydrogenase 1 (RALDH1), inducible nitric oxide synthase (iNOS), B cell activating factor of the tumor necrosis family (BAFF), a proliferation-inducing ligand (APRIL), and receptors for the neuropeptide vasoactive intestinal peptide (VIP). The ability of PP-DC to promote anti-CD40 dependent IgA was partially dependent on retinoic acid (RA) and transforming growth factor (TGF)-beta, whilst BAFF and APRIL signaling were not required. Signals delivered by BAFF and APRIL were crucial for CD40 independent IgA production, although the contribution of B2 cells to this pathway was minimal. The unique ability of PP-DC to instruct naïve B cells to differentiate into IgA producing plasma cells was mainly imparted by the presence of intestinal commensal bacteria, and could be mimicked by the addition of LPS to the culture. These data indicate that exposure to pathogen-associated molecular patterns present on intestinal commensal bacteria condition DC to express a unique molecular footprint that in turn allows them to promote IgA production.